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United States Patent |
6,092,387
|
Hironaka
,   et al.
|
July 25, 2000
|
Air conditioner with electric dust collector
Abstract
An air conditioner includes an electric dust collector arranged between an
evaporator and a heat shield plate. This electric dust collector includes
a discharge electrode and a dust collecting electrode. The discharge
electrode is applied with a positive polarity of high direct current
voltage from a high voltage power source, while the dust collecting
electrode is supplied with a negative polarity of high direct current
voltage. Accordingly, the dust charged through plus electric discharge by
the discharge electrode is attracted onto the dust collecting electrode or
a casing thereof.
Inventors:
|
Hironaka; Yasumasa (Daito, JP);
Sakaue; Takao (Daito, JP)
|
Assignee:
|
Funai Electric Co., Ltd. (Osaka, JP)
|
Appl. No.:
|
251804 |
Filed:
|
February 17, 1999 |
Foreign Application Priority Data
| Feb 19, 1998[JP] | 10-036939 |
Current U.S. Class: |
62/317; 96/15; 96/96 |
Intern'l Class: |
F25D 017/04 |
Field of Search: |
62/317,78,264
96/15,74,96
|
References Cited
U.S. Patent Documents
5290343 | Mar., 1994 | Morita et al. | 96/96.
|
5529613 | Jun., 1996 | Yavnieli | 85/96.
|
Foreign Patent Documents |
58-55058 | Apr., 1983 | JP.
| |
58-88045 | May., 1983 | JP.
| |
363127043 | May., 1988 | JP.
| |
410332165 | Dec., 1998 | JP.
| |
Primary Examiner: Doerrler; William
Assistant Examiner: Jiang; Chen-Wen
Attorney, Agent or Firm: Siegel; Lackenbach
Claims
What is claimed is:
1. An air conditioner, comprising:
a housing having a back plate supported by a mount member and air intake
port and an air outlet port:
a heat exchanger arranged within said housing:
an electric dust collector arranged between said heat exchanger and said
back plate and having a discharge electrode and a dust collecting
electrode;
a high voltage power source for supplying a first polarity of a high direct
current voltage to said discharge electrode and a second polarity of a
high direct current voltage to said dust collecting electrode; and
wherein said dust collecting electrode has a heater coated with a catalyst
for effecting oxidation and decomposition, a heat shield plate provided in
the vicinity of said back plate to field heat from said heater, and said
dust collecting electrode being positioned between said heat exchanger and
said heat shield plate.
2. An air conditioner according to claim 1, wherein said heat shield plate
is in a state of electrically floating.
3. An air conditioner according to claim 1, where said high voltage power
source supplies to said discharge and dust collecting electrodes a voltage
having a magnitude that a discharge current flows through between said
discharge electrode and said dust collecting electrode but no discharge
current flows between said discharge electrode and said heat exchange.
4. An air conditioner according to claim 2, where said high voltage power
source supplies to said discharge and dust collecting electrodes a voltage
having a magnitude that a discharge current flows through between said
discharge electrode and said dust collecting electrode but no discharge
current flows between said discharge electrode and said heat exchange.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an air conditioner with electric dust
collector, and more particularly to an air conditioner which, for example,
is fixed in a room interior and provided with an electric dust collector
having discharge and dust collecting electrodes.
2. Description of the Prior Art
There is disclosed one example of a conventional electric dust collector in
Japanese Patent Publication No. S58-55058 [B03C3/41, B03C 3/66]. In this
electric dust collector, a high direct current voltage in negative
polarity is applied to the discharge electrode while a high direct current
voltage in positive polarity is applied to the dust collecting electrode.
That is, minus electric discharge enables collection of dust even if it is
high in electrical resistivity.
This prior art, employing the minus discharge technique, is high in
efficiency in collecting the dust. However, discharge electrons cause
oxygen to be charged in minus, causing active oxygen or ozone. Active
oxygen and ozone are considered by no means harmless because they might
induce a problem, particularly in health, to human bodies.
Meanwhile, where such an electric dust collector is incorporated within an
air conditioner, the discharge and dust collecting electrodes are usually
positioned at such locations where cleaning is possible for the electrode
from external whenever the dust collecting electrode requires cleaning.
SUMMARY OF THE INVENTION
Therefore, it is a primary object of the present invention to provide a
novel air conditioner with electric dust collector.
It is another object of the present invention to provide an air conditioner
with electric dust collector which has an electric dust collector that can
be arranged even within a narrow space and one in which is not harmful to
the human body.
An air conditioner according to the present invention, comprises: a housing
having a back plate supported by a mount member and air intake port and an
air outlet port; a heat exchanger arranged within the housing; an electric
dust collector arranged between the heat exchanger and the back plate and
having a discharge electrode and a dust collecting electrode; and a high
voltage power source for supplying a first polarity of a high direct
current voltage to the discharge electrode and a second polarity of a high
direct current voltage to the dust collecting electrode.
The housing back plate is supported by a mount member through which the
housing is fixed on a wall surface. The electric dust collector is
arranged between the heat exchanger and the back plate. In a dust
collecting mode, the discharge electrode of the electric dust collector is
supplied with a first, e.g., positive, polarity of high direct current
voltage, while the dust collecting electrode thereof is given with a
second, e.g., negative, polarity of high direct current voltage.
Accordingly, the dust is collected through plus electric discharge.
In the case of providing a heater onto the dust collecting electrode, in a
restoring mode the dust collected on the electrode is oxidized and
decomposed by the heater heat. In this case, however, a heat shield plate
is preferably provided close to the back plate in order to shield the heat
and further the dust collecting electrode is positioned between the heat
exchanger and the heat shield plate.
Also, the heat shield plate is in a state of electrically floating.
In either case, the high voltage power source supplies to the discharge and
dust collecting electrodes a voltage having a magnitude that a discharge
current flows through between the discharge electrode and the dust
collecting electrode but no discharge current flows between the discharge
electrode and the heat exchanger.
According to the present invention, the dust collecting discharge voltage
given between the discharge electrode and the dust collecting electrode is
shared by positive and negative polarities of direct voltages. It is
accordingly possible to provide an electric dust collector at a narrow
space within the housing without inducing unwanted electric discharge
(current leak) between the discharge electrode and the heat exchanger.
Furthermore, dust collection is through plus electric discharge and
therefore harmless for human bodies with less producing ozone or the like.
Also, the dust collecting electrode, if added with a self-cleaning function
to oxidize and decompose dust, eliminates the necessity of manually
implementing cleaning.
The above described objects and other objects, features, aspects and
advantages of the present invention will become more apparent from the
following detailed description of the present invention when taken in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an illustrative view showing one embodiment according to the
present invention;
FIG. 2 is a graph showing an electric current against a gap voltage in an
unequal electric field; and
FIG. 3 is an illustrative view showing a high voltage power source.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1, an air conditioner 10 with electric dust collector in
this embodiment includes a housing 12. The housing 12 is formed of a
synthetic resin, such as a plastic resin. This housing 12 has openings 14a
and 14b in its front face. The opening 14a serves as an air intake port
while the opening 14b at beneath the opening 14a as an air outlet port.
The opening 14a and 14b are hereinafter referred, respectively, to as air
intake port and air outlet port. Also, the housing 12 is formed with a
back plate 14c which is held by a mount member 14d for mounting on a
not-shown wall surface. This structure makes the housing 12 to be mounted
on the wall surface.
A filter 16 is detachably provided between the air intake port 14a and a
heat exchanger (evaporator) 18 in a manner covering over the air intake
port 14a. The filter 16 is formed of a filter fiber, such as a glass fiber
or plastic fiber. An evaporator 18 is arranged on the back side of the
filter 16 within the housing 12 so that it can exchange heat of the air
introduced through the air intake port 14a into the housing 12. The
evaporator 18 is connected to the ground. A cross flow fan 20 is arranged
at a location further behind the evaporator 18 and deep inward the air
outlet port 14b so that the cross flow fan 20 rotates about a rotation
axis 20a. By providing rotation to this cross flow fan 20, an air stream
is created extending from the air intake port 14a through the evaporator
18 to the air outlet port 14b and spreading widthwise (in rotation axis
20a direction).
Further, an electric dust collector 26 is provided within the housing 12.
The electric dust collector 26 includes a discharge electrode 22 and a
dust collecting electrode 24 which are held spaced at a constant distance
(1.5 cm in this embodiment) relative to each other. The discharge
electrode 22 is made up of a steel wire, stainless wire or tungsten wire,
and extends in a width direction (rotation axis 20a direction) of the air
conditioner 10 with electric dust collector. The dust collecting electrode
24, on the other hand, includes a heater 28 made in a rod form. This
heater 28 is accommodated within a casing 30 that is generally in a
cylindrical form and coated with a ceramics layer through a catalyst. A
high voltage power source 32 is connected to the electric dust collector
26 thereby enabling dust collection. The dust collecting electrode 24 is
mounted on a heat shield plate 34. The heat shield plate 34 is in contact
with the evaporator 18 through an insulation member 38, and secured to the
housing 12 of an insulation material. Due to this, the heat shield plate
34 is kept in a state of electrically floating. Immediately after starting
electric discharge by the discharge electrode 22, the discharge is
slightly effected toward the heat shield plate 34. However, the discharge
to the heat shield plate 34 almost ceases in a brief time because
saturation is reached by the heat shield plate 34 and further the
difference in discharge voltage is small.
A high direct current voltage in a positive polarity (+4.5 kV in this
embodiment) is supplied from the high voltage power source 32, while a
negative polarity high direct current voltage (-4.5 kV in this embodiment)
is given to the dust collecting electrode 24. In this manner, the high
direct current voltage shared by the positive and negative polarities
makes it possible to decrease the difference in voltage between each
electrode and the ground. This can prevent abnormal discharge from
occurring at a position other than between the electrodes. The high
voltage power source 32 of this embodiment has a voltage value as shown in
FIG. 2 which is expectable from a curve of a current characteristic vs. a
gap voltage in an unequal electric field. That is, no discharge current
appears at 4.5 kV or below. At around 9.0 kV a film-formed corona
discharge takes place providing stable discharge currents. However, the
humidity within the air conditioner 10 is comparatively high. It is
possible to deduce, through experiments, a distance between the discharge
electrode 22 and the dust collecting electrode 24, as well as a voltage
value of the high voltage power source 32. Thus, electric discharge can be
caused only between the discharge electrode 22 and the dust collecting
electrode 24, enabling efficient dust collection. Incidentally, in this
embodiment the positive and negative polarity high direct current voltages
were set the same in absolute value. However, these voltages may be set in
different values provided that the potential difference between them be
given around 9.0 kV. Meanwhile, the heater 28 within the dust collecting
electrode 24 is connected to an alternate current power source 36 as a
commercial power supply (100V) by which power is given to the heater 28.
Explaining in detail on the high voltage power source 32, the high voltage
power source 32 shown in FIG. 3 includes an input terminal 40 via which an
alternate current voltage is applied. The alternate current voltage
supplied through the input terminal 40 is inputted to a rectifying circuit
42 where the voltage is subjected to rectification. That is, the alternate
current voltage is converted into a direct current voltage. This direct
current voltage is delivered to an oscillation circuit 44 whereby the
oscillation circuit 44 is oscillated at a predetermined frequency. This
oscillation current is given to a transformer 46 where it flows through a
primary coil thereof. Due to this, a radio frequency high voltage is
outputted from a secondary side of the transformer 46 in proportion to the
ratio in the number of windings of the primary to secondary coil. This
output is boosted and rectified by a multiple step-up rectifying circuit
48, providing direct current high voltages with positive and negative
polarities onto respective high voltage output terminals 50 and 52.
In a dust collecting mode, a positive polarity high direct current voltage
(+4.5 kV) is supplied to the discharge electrode 22 from a positive
voltage output terminal 50 of the high voltage power source 32 while a
negative polarity high direct current voltage (-4.5 kV) is supplied to the
dust collecting electrode 24 from a negative voltage output terminal 52.
This causes a potential difference of approximately 9.0 kV between the
discharge electrode 22 and the dust collecting electrode 24, producing
electric discharge between these electrodes. Thus, the dust electrically
charged by the discharge electrode 22 is attracted to the dust collecting
electrode 24. In a restoring mode, the high voltage power source 32 is
turned off and the heater 28 is applied by an alternate current voltage
(AC100V) from the alternate current power source 36. Consequently, the
casing 30 (dust collecting electrode 24) at its surface is heated up, for
example, to 200 to 350.degree. C. By thus heating, the dust collected over
the surface of the casing 30 is subjected to oxidation and decomposition
into water and carbon dioxide. In other words, this dust collecting
electrode 24 has a function of self-cleaning. If a control circuit (not
shown) such as a micro-computer is employed to switch between the high
voltage power source 32 and the alternate current power supply 36, and
accordingly between the dust collecting mode and the reproduce mode, the
dust collectability can be kept high for a long term.
According to this embodiment, a high direct current voltage in a positive
polarity is applied to the discharge electrode 22 while a high direct
current voltage in a negative polarity is to the dust collecting electrode
24. This can decrease the difference of voltage between each electrode and
a position other than those. Therefore it is possible to arrange an
electric dust collector 26 in such a narrow space as between the
evaporator 18 and the heat shield plate 34.
Also, the electric dust collector 26 is made to effect plus discharge
without producing ozone or the like, thus doing no harm to the human body.
In the above embodiment, the discharge electrode 22 is supplied by a
positive polarity voltage and the dust collecting electrode 24 is by a
negative polarity voltage. However, the polarity for each electrode may be
set reverse to that of the embodiment.
It should be noted that in this Specification the "direct current voltage"
covers in concept not only a constant value voltage but also a pulsating
or pulse voltage having a voltage value varying in one polarity.
Although in this embodiment the high voltage power source 32 and the
alternate current power supply 36 were provided outside the air
conditioner 10 with electric dust collector in the figure, these high
voltage power source 32 and alternate current power supply 36 may be
arranged within the air conditioner 10 with electric dust collector.
Although the present invention has been described and illustrated in
detail, it is clearly understood that the same is by way of illustration
and example only and is not to be taken by way of limitation, the spirit
and scope of the present invention being limited only by the terms of the
appended claims.
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